809. Phenomena precisely analogous occur, when, from intense mental excitement, the brain is kept long in a state of excessive activity. The only difference is, that we can always see what happens in the eye, but rarely what takes place in the brain; occasionally, however, cases of fracture of the skull occur, in which, part of the bone being removed, we can see the quickened circulation in the vessels of the brain, as easily as those of the eye. -=-=-=-=-=-=-=-=-=-=-=-= 807. What is one great evil attending the absence of some imperative employment to exercise the mind and brain? What is the true remedy for these evils? 808. From what other cause do evils arise to the brain? Explain the evil of it by the excessive use of the eye. 809. What is the only difference in the analogy of the phenomena of the eye and brain? Has the analogy been verified? -=-=-=-=-=-=-=-=-=-=-=-= 810. Sir Astley Cooper had a young man brought to him, who had lost a portion of his skull, just above the eyebrow. "On examining the head," says Sir Astley, "I distinctly saw that the pulsation of the brain was regular and slow; but at this time he was agitated by some opposition to his wishes, and directly the blood was sent with increased force to the brain, and the pulsation became frequent and violent." 811. Indeed, in many instances, the increased circulation in the brain, attendant on mental excitement, reveals itself when least expected, and leaves traces after death, which are very perceptible. When tasked beyond its strength, the eye becomes insensible to light, and no longer conveys any impressions to the mind. In like manner, the brain, when much exhausted, becomes incapable of thought, and consciousness is almost lost in a feeling of utter confusion. 812. _At any time of life, excessive and continued mental exertion is hurtful_; but in infancy and early youth, when the structure of the brain is still immature and delicate, permanent mischief is more easily produced by injudicious treatment than at any subsequent period. In this respect, the analogy is as complete between the brain and the other parts of the body, as that exemplified in the injurious effects of premature exercise of the bones and muscles. 813. Scrofulous and rickety children are the most usual sufferers in this way. They are generally remarkable for large heads, great precocity of understanding, and small, delicate bodies. But in such instances, the great size of the brain, and the acuteness of the mind, are the results of morbid growth. Even with the best of management, the child passes the first years of its life constantly on the brink of active disease. -=-=-=-=-=-=-=-=-=-=-=-= 810. Relate the case detailed by Sir Astley Cooper. 811. May the increased functional action of the brain change its structure? 812. At what age particularly is excessive and continued mental exertion hurtful? 813. What is said of scrofulous and rickety children? -=-=-=-=-=-=-=-=-=-=-=-=